1. Field
Example embodiments relate to thin-film transistors (TFTs) having an etch stop multi-layer and methods of manufacturing the TFTs.
2. Description of the Related Art
Thin-film transistors (TFTs) may be used in various application fields, and specifically, used as switching and driving devices in displays. Recently, liquid crystal displays (LCDs) have been used as panels for televisions (TVs), while organic light emitting displays (OLEDs) have been studied to be applied in TVs. Displays for TVs have been developed to satisfy requirements in the TV market. Such requirements may be relatively large TVs or digital information displays (DIDs), lower costs, and high-definition (moving image presentation, high-resolution, brightness, contrast ratio, or color reproductivity). In order to satisfy these requirements, a large substrate formed of glass along with a highly efficient TFT to be used as a switching and driving device of a display may be required.
TFTs having characteristics of both an amorphous silicon TFT and a polycrystalline silicon TFT are being actively studied. One of these TFTs may be an oxide semiconductor device, for example, a zinc oxide (ZnO)-based TFT. Examples of a ZnO-based material may include ZnO, indium-zinc oxide (IZO), a ZnO doped with gallium (Ga), magnesium (Mg), aluminum (Al), or iron (Fe), and an IZO doped with Ga, Mg, Al, or Fe. A ZnO-based semiconductor device may be manufactured at a relatively low temperature, may be in an amorphous state, and thus may be more easily manufactured to have a large size. Also, a ZnO-based semiconductor film has higher mobility, and thus has improved electrical characteristics like those of polycrystalline silicon. Studies to use an oxide semiconductor material layer having higher mobility, e.g., a ZnO-based material layer, for a channel region of a TFT are being actively performed.